In this paper, the electro-viscous effects on pressure-driven liquid flow through a microchannel which is composed of two heterogeneous sections are analyzed. The Poisson-Boltzmann equation, Navier-Stokes equations and a set of constrained equations are solved analytically to obtain the velocity profiles and the streaming potentials in each section. Effects of the zeta potential and length ratio of the two sections on the flow resistance are discussed by means of the apparent viscosity ratio and the Poiseuille number. (C) 2008 Elsevier Ltd. All rights reserved.